Question: Brandon has taken 6 quizzes and his average score so far is 79. If he gets 100, a perfect score, on the remaining 3 quizzes, what will his new average be?
Explanation: If he gets 100 on the remaining quizzes, the sum of his scores will be $6 \cdot 79 + 3 \cdot 100 = 774$ His overall average will then be $774 \div 9 = 86$.